try to clr_cmos... pull the plug out of the computer, set the jumper, and pull the battery. wait a few minutes, then set it all back up
if that doesn't work
pull out all but 1 stick of ram, unplug all the drives... if that doesn't work, swap the stick of ram into each different ram slot, then try the other sticks in different slots.
If none of this works you might have a faulty motherboard.